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141.
Yamaoka Y Taniguchi Y Yasuzuka S Yamamura Y Saito K 《The Journal of chemical physics》2011,135(4):044705
Quasi-binary (QB) picture of thermotropics, which regards a neat thermotropic liquid crystal as a binary system consisting of (semi)rigid core and molten alkyl chain, was assessed experimentally for the most famous (and representative) thermotropic mesogenic series nCB. By adding n-heptane as solvent, the smectic A phase was induced in 7CB-n-heptane system. Small angle x-ray diffraction showed that the QB picture holds not only in the phase behavior but also in the structure. It is suggested that the melting of 8CB and 9CB to isotropic liquid via smectic and nematic liquid crystals can be understood as a thermotropic-lyotropic crossover. 相似文献
142.
Kitamura T Morshed MH Tsukada S Miyazaki Y Iguchi N Inoue D 《The Journal of organic chemistry》2011,76(19):8117-8120
Phenyl(trimethylsilylethynyl)iodonium and tert-butyldimethylsilylethynyl(phenyl)iodonium triflates were applied to alkynylation of benzotriazole. Treatment of the silylethynyliodonium triflates with the potassium salt of benzotriazole ion in (t)BuOH and CH(2)Cl(2) gave 2-(trimethylsilylethynyl)-2H-1,2,3-benzotriazole and 2-(tert-butyldimethylsilylethynyl)-2H-1,2,3-benzotriazole in 74% and 76% yields, respectively. The regioisomers, 1-silylethynyl-1H-1,2,3-benzotriazole derivatives, were minor. In both cases of the silyl-substitued ethynyliodonium salts, novel regioselective alkynylation of benzotriazole at the 2 position was observed. 相似文献
143.
Stepwise, selective DIBAL reduction of the acetonide diester derived from tartaric acid followed by the Horner-Emmons reaction effectively provided desymmetrized hydroxy mono-olefination products in a one-pot operation. 相似文献
144.
Miyazaki M Ando N Sugai K Seito Y Fukuoka H Kanemitsu T Nagata K Odanaka Y Nakamura KT Itoh T 《The Journal of organic chemistry》2011,76(2):534-542
A catalytic asymmetric allylation of 3,4-dihydroisoquinoline was carried out with allyltrimethoxylsilane-Cu as the nucleophile in the presence of DTBM-SEGPHOS as the chiral ligand to afford corresponding chiral 1-allyltetrahydroisoquinoline derivatives in good yield and stereoselectivity. The allyl adduct thus obtained was applied to the synthesis of several isoquinoline alkaloids such as crispine A and homolaudanosine. The reaction was further used for the synthesis of the isoquinoline moiety of schulzeine A. 相似文献
145.
Iwayama Y Ando H Tanaka HN Ishida H Kiso M 《Chemical communications (Cambridge, England)》2011,47(34):9726-9728
The glycan moiety of ganglioside HPG-7, isolated from the sea cucumber (Holothuria pervicax), was synthesized for the first time. The characteristic substructure, a trisialic acid sequence embedded in the glycan, was deliberately constructed by utilizing suitably differentiated sialyl units for various synthetic purposes. Finally, a pentasaccharide was successfully delivered as the hexyl glycoside. 相似文献
146.
Kosumi D Kusumoto T Fujii R Sugisaki M Iinuma Y Oka N Takaesu Y Taira T Iha M Frank HA Hashimoto H 《Physical chemistry chemical physics : PCCP》2011,13(22):10762-10770
Carotenoids containing a carbonyl group in conjugation with their polyene backbone are naturally-occurring pigments in marine organisms and are essential to the photosynthetic light-harvesting function in aquatic algae. These carotenoids exhibit spectral characteristics attributed to an intramolecular charge transfer (ICT) state that arise in polar solvents due to the presence of the carbonyl group. Here, we report the spectroscopic properties of the carbonyl carotenoid fucoxanthin in polar (methanol) and nonpolar (cyclohexane) solvents studied by steady-state absorption and femtosecond pump-probe measurements. Transient absorption associated with the optically forbidden S(1) (2(1)A) state and/or the ICT state were observed following one-photon excitation to the optically allowed S(2) (1(1)B) state in methanol. The transient absorption measurements carried out in methanol showed that the ratio of the ICT-to-S(1) state formation increased with decreasing excitation energy. We also showed that the ICT character was clearly visible in the steady-state absorption in methanol based on a Franck-Condon analysis. The results suggest that two spectroscopic forms of fucoxanthin, blue and red, exist in the polar environment. 相似文献
147.
148.
Chikara Shito Keitaro Okamoto Yuki Sato Ryuji Watanabe Tomonori Ohashi Kazuhiro Fuchizaki 《高压研究》2013,33(3):499-508
ABSTRACTHigh pressure hydrous phases with distorted rutile-type structure have attracted much interest as potential water reservoirs in the Earth’s mantle. An in-situ X-ray diffraction study of β-CrOOH was performed at high pressures of up to 6.2?GPa and high-temperatures of up to 700?K in order to clarify the temperature effect on compression behaviors of β-CrOOH. The P-V-T data fitted to a Birch–Murnaghan equation of state yielded the following results: isothermal bulk modulus KT0?=?191(4)?GPa, temperature derivative (?KT/?T)P?=??0.04(2)?GPa?K?1, and volumetric thermal expansion coefficient α?=?3.3(2)?×?10?5?K?1. In this study, at 300?K, the a-axis became less compressible at pressures above 1–2?GPa. We found that the pressure where the slopes of a/b and a/c ratios turned positive increased with temperature. This is the first experimental study indicating the temperature dependence of the change in the axial compressibility in distorted rutile-type M3+OOH. 相似文献
149.
Osamu Kido Mami Kurumada Katsuya Kamitsuji Toshiaki Tanigaki Takeshi Sato Yuki Kimura Hitoshi Suzuki Yoshio Saito Chihiro Kaito 《Physica E: Low-dimensional Systems and Nanostructures》2006,31(2):169-173
The synthesis of Al–Cr single quasicrystal (QC) nanoparticles of the decagonal phase was achieved by introducing an advanced gas flow evaporation method. By obtaining successive electron diffraction patterns for single-QC nanoparticles, the phase transformation temperature of a single-QC nanoparticle was determined to be 700 °C. It was also determined that part of the QC nanoparticle decomposed into hex-Al8Cr5 and Al during the phase transformation. Since the grain growth did not occur during the phase transformation in the present experiment, the inherent phase transformation temperature could be measured. 相似文献
150.
Shinjiro Hayakawa Yuki Hajima Shan Qiao Hirofumi Namatame Takeshi Hirokawa 《Analytical sciences》2008,24(7):835-837
Ca K edge X-ray absorption fine structure (XAFS) spectroscopy was utilized for the characterization and quantification of calcium carbonate polymorphs and their mixtures. The advantage of the XAFS is the small sample quantity required for measurements, and a flexible sample environment. The near-edge XAFS spectra of calcite, aragonite and vaterite were measured with the conversion electron yield (CEY) method, and the obtained spectra showed characteristic features that can be utilized as fingerprints. The quantification of mixed polymorphs was examined by using a linear combination fitting of reference XAFS spectra. Though the quality of the fits was satisfactory, discrepancies in the evaluated values were observed between those with X-ray diffraction (XRD) and XAFS. The nonuniformity of samples may be enhanced by the surface sensitivity of the CEY method. 相似文献